The Spaniard, who rose to the top of the rankings just last week following the US Open, was pushed by Puig in a tough opening set by Tokyo, though prevailed through that and eventually proved far too strong for the Puerto Rican; Muguruza eventually eased through to a 6-4, 6-0 victory in an hour and 14 minutes in the Japanese capital.

Having received a bye in the opening round, Muguruza, so far the only person to have secured qualification for the WTA Finals, is now in the last eight and will face wildcard Kurumi Nara or ninth seed Caroline Garcia for a place in the semifinals.

Muguruza gets Tokyo campaign off to a solid start

There can be no doubt that Puig provided Muguruza with a much tougher test than the scoreline suggests, though Muguruza’s strength showed as she was able to take more opportunities and eventually break through the Puerto Rican’s resistance to record a very solid win.

Muguruza started very well, breaking early and saving break points herself for a 2-0 lead, though some early nerves meant that Puig was able to break back and even up proceedings at 2-2. However, the Spaniard broke Puig’s resistance once again and was able to consolidate, building up a 4-2 lead. The Puerto Rican dropped just two games when she beat Muguruza in Rio last summer, though was facing an almost different opponent now and could not find her way back as the Spaniard took the opening set.

Muguruza in action during her first match at the top of the rankings (Getty/Matt Roberts)

Just as she did in the first set, Muguruza broke early on and consolidated to love for a 2-0 lead, though did not make any mistakes this time as she came through a hard-fought game to secure a double break lead. The top seed was not always finding things easy, though was always able to win the decisive points through the closing set and after another hold, converted a fourth break point to go 5-0 up. An ace on her second match point secured a first win as the world number one for the Wimbledon champion.

It was not a flawless performance by Muguruza, who converted just five of her 13 break point chances and made 13 unforced errors, though a total of 17 winners and a first serve percentage of 73% is undoubtedly encouraging as the Spaniard continues her quest for a third title of 2017 and the sixth in her career overall.